list_domainsRetrieve domains registered to your organization, optionally filtering by exact FQDN. Returns domain IDs used by other Mailfact tools.
Domains registered on this token's organisation. Pass fqdn for an exact hostname match (case-insensitive, trailing dot stripped). Returns ids the other tools take as domain.
| Name | Required | Description | Default |
|---|---|---|---|
| fqdn | No | Exact domain name, e.g. mailfact.app. |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnly, non-destructive, openWorld), so the bar is lower. The description still adds real context the annotations lack: the result set is scoped to the token's organisation, matching is case-insensitive with a trailing dot stripped, and the returned ids are the identifiers other tools accept. It does not address pagination or result size limits.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three short sentences with no filler; the resource scope, the filter behavior, and the return contract each appear once and in a sensible order. Nothing could be cut without losing information.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
No output schema exists, so the description must carry the return contract, and it does so at a useful level: the ids other tools consume. Minor gaps remain around result count, ordering, and pagination, but for a one-parameter read tool this is close to complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% and already documents fqdn as an exact domain name. The description adds semantics the schema omits, notably case-insensitive matching and trailing-dot normalization, which materially affect how the caller should format the value.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb (list) and resource (domains), plus the scoping qualifier 'registered on this token's organisation'. An agent can distinguish it from get_domain by the list-vs-single semantics, though the sibling is never named.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It gives a usage cue for the fqdn parameter ('Pass fqdn for an exact hostname match') but never states when to prefer this tool over get_domain or the other listing tools. Usage is implied by the resource scope rather than made explicit.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.